backup electric for gas furnace

Power outages are becoming more common and lasting longer in our area. When the power goes out we have no heat because the controls on the boiler are electric. The electric requirements are minimal. We have a Heat Timer which has a small clock motor, an outside sensor and a solenoid gas inlet valve. I am thinking that if we had a few storage batteries hooked up to a trickle charger, an inverter to bring the power to 110v AC and a transfer switch, either manual or automatic we would be in business. Has anyone done this? Is there an off the shelf item such as a UPS for a computer that would work? Does this idea have merit? I think it would be less hassle than dealing with a genny.

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I have not but I have dealt with, setup configurations using, batteries to power computer equipment. The benefit was speed of transfer. On the downside limited capacity and not cheap for what you were getting. Did not last long even though the drain was small. The solution for companies was both. Use the batteries for the fast switch and keep it running long enough to get the generators up and running, often automated but still requiring some minutes to get them all going, and flip from the batteries.

Be interesting to what can be done today. (personally I wired up a 5600 genny through a transfer switch purchased as a kit. It was easy to me and I don't have anything near the capability to understand the stuff you are contemplating).

Thanks for the good info Dan. I live in a small self managed condo so I'm not so worried about the cost as it will be split seven ways. I am hoping to go the battery route as I will end up having to manage the genny if it comes to that.

A long time ago I lived in an apartment that had a one pipe steam system, a
Gas steam boiler.
One winter we had a power outage, my heat still worked!!

The gas fired steam boiler had a standing gas pilot light.
Inside the pilot light's flame was a thermalcouple for the gas valve.
I think it was called a power pile.
Basically the pilot light flame created electricity from the thermcouple.
This electricty powered the main gas valve and also the thermostat.
All "self contained", not dependent on AC power.
No wires to the panelboard at all.
There was an emergency OFF switch which was wired into the themostat wire circuit.

Maybe you could retrofit to the powerpile.
Perhaps the term millivolt system was used also. Not sure. I'm talking over 35 years ago.
Perhaps others may remember this power pile setup.
I'm not making this up.

So far as how long a UPS will last, those UPS sold in consumer stores like Walmart would last a very short time with a computer. But they sell UPS with more or larger batteries at office supply stores or on the internet.

Also add up the wattage or amperage of what is on the furnace. I'm thinking this would be much less than what a computer with a monitor draws. Then you will get an idea of how long it should last on various UPS.

A long time ago I lived in an apartment that had a one pipe steam system, a
Gas steam boiler.
One winter we had a power outage, my heat still worked!!

The gas fired steam boiler had a standing gas pilot light.
Inside the pilot light's flame was a thermalcouple for the gas valve.
I think it was called a power pile.
Basically the pilot light flame created electricity from the thermcouple.
This electricty powered the main gas valve and also the thermostat.
All "self contained", not dependent on AC power.

Maybe you could retrofit to the powerpile.
Perhaps the term millivolt system was used also. Not sure. I'm talking over 35 years ago.
Perhaps others may remember this power pile setup.
I'm not making this up.

The main gas valve would have to be designed for use with the powerpile, namely operate on about one volt instead of 24 volts.

Modern water heaters use a similar setup but where the thermocouple generates only about 1/20'th of a volt and controls only a small gas valve that in turn shuts off the pilot light orifice if the pilot light should be blown out. The sole purpose of the thermocouple is to prevent raw gas from escaping into the heater and into the basement. A "hydraulic" thermostat using expanding gel inside a cylinder with piston or diaphragm is used to activate the main gas valve. Another mechanical part blocks the main gas flow if the thermostat calls for heat/gas when the pilot light had gone out and the pilot orifice was closed off.

__________________The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

What you would need is two deep cycle batteries. A dual battery isolator and an inverter and an automatic charger. Two deep cycle batteries should be able to get you through an outage without an issue. The automatic charger will recharge the batteries when the power comes back on. The isolator allows the batteries to be charged independently and prevent overcharging, it also allows the charger to keep the battery at optimum voltage levels.

Since this is most likely a 24 volt gas valve on this system, why go thru the trouble of converting battery voltage to line voltage just to transform it back to 24 volts. Two batteries in series will provide the voltage to operate the gas valve and control circuit. Since there is no circ pump on this system 120 volts is not needed.

Two 12 volt batteries providing 24 volts will work only if the furnace accepts 24V direct current.

More likely the furnace only accepts 24VAC from a doorbell type transformer.

It is easier to find off the shelf components to invert 12 VDC or 24 VDC to 120 VAC and then transform the latter to 24 VAC (using the existing transformer) as opposed to have to kit bash a 24 VDC to 24 VAC inverter.

__________________The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Thanks to all for the helpful replies. The gas valve is 24v but the boiler control is 110v so the inverter seems the way to go. The Xantrex 1000 that Red Squirrel linked to seems perfect. It combines an inverter, charger and automatic transfer switch all in one unit so no matching of components is required. I just have to find that or a similar unit in the US and I also have to find out if the inverter can run continuously at low draw for the extent of the outage as the boiler control has a clock motor in it running 24/7.